While most folks care about what the weather will be like here near the ground, it would be very difficult for us forecasters to accurately predict that weather if we didn't also know what was happening at upper levels of the atmosphere. While satellite, radar and wind profiler technology can certainly provide us with valuable information, one tried and true method of gathering data has stood the test of time - weather balloons! Weather balloons are launched from hundreds of locations around the world twice a day, every day of the year. The launches occur nearly simultaneously worldwide! This gives meteorologists a snapshot of the earth's three-dimensional atmospheric conditions.

Weather balloons are launched from the roof of our building from the shelter pictured above. The balloons are filled with helium inside of the shelter, then released. The helium, which is a very light gas, allows the balloon to reach heights of 60,000 feet above the earth's surface in about an hour. As the balloon rises, the atmosphere thins and the pressure outside the balloon decreases allowing the balloon to expand and eventually break. This usually happens within two hours of the launch at elevations of 80,000 to 120,000 feet.

An instrument, called a radiosonde, is tethered to the balloon. As the balloon rises through the air, the radiosonde measures temperature, relative humidity, and pressure. A GPS transmitter within the radiosonde transmits this data back to a tracking unit located atop the building. This unit tracks the azimuth and range of the balloon as it ascends. From this information, the wind speed at various levels in the atmosphere can be calculated. After the balloon flight is complete, a technician ensures the data is accurate before it is disseminated at the workstation pictured below. Additional quality control checks are done at one of our national centers before the data is incorporated into computer models which meteorologists use to make their forecasts.